diff --git a/common/source/java/ch/systemsx/cisd/common/serviceconversation/ClientMessenger.java b/common/source/java/ch/systemsx/cisd/common/serviceconversation/ClientMessenger.java
index ad27c3a724a2ba891101849f5eddf137a6ee6098..774566cc2c7799b149a4fb6eadf57e427f2f9c7f 100644
--- a/common/source/java/ch/systemsx/cisd/common/serviceconversation/ClientMessenger.java
+++ b/common/source/java/ch/systemsx/cisd/common/serviceconversation/ClientMessenger.java
@@ -63,7 +63,7 @@ public class ClientMessenger implements IClientMessenger
             {
                 public void send(ServiceMessage message)
                 {
-                    if (serviceConversationId.equals(message.getConversationId()))
+                    if (serviceConversationId.equals(message.getConversationId()) == false)
                     {
                         throw new IllegalArgumentException(
                                 "Attempt to put in a message for conversation "